Complications with vascular access include hematomas, pseudoanuerysms, retroperitoneal bleeding, and arteriovenous pseudoanuerysm. Causes for complications include: (1) difficulty in locating the entry site to the target vessel (e.g., artery or vein), and (2) inadvertent perforation or dissection of a wall (e.g., posterior wall) of the vessel into collateral structures (e.g., adjacent veins or the retroperitoneal space). Also, wire and sheath placement may further lead to such complications. Furthermore, attempts at hemostasis (e.g., manual or by closure devices) may assume direct, focal penetration of the needle at only one vessel site and consequently, may be unsuccessful.
Vessel prelocation methods for vascular access include the landmark technique, x-ray assistance, and ultrasound guidance. The landmark technique may be carried out through palpation and consideration of anatomical landmarks around the insertion site. Fluoroscopy, which uses x-ray scans to visualize the situation, may be used. Also, ultrasound may provide audible feedback to estimate the location of the needle in relation to the target vessel. However, ultrasound may require complicated training, may have limitations during hypotensive emergencies, can be expensive, and may suffer complications when used for the arterial system. Doppler needles have had limited success as well.